(1) Field of the Invention
The present invention relates to cardiac monitoring and telemedicine systems and, more particularly, to cardiac monitoring systems which provide an analysis and display of one or more parameters relating to the condition of ischemic patients.
(2) Description of the Related Art
A number of new clog dissolving agents presented by the pharmaceutical industry during the past couple of years have given cardiologists the ability to immediately treat acute myocardial ischemia through chemical thrombolytic therapy. However, it is frequently difficult to properly control and adjust such therapy during the acute phase of a myocardial ischemia. Known methods are either expensive or have too large a delay (up to several hours) between the time of the myocardial ischemia time and the presentation of the results.
Some cardiac monitoring systems and methods also utilize a known 12-lead electrocardiogram in which electrocardiogram (ECG) signals are displayed directly on a monitor in real-time. Such a 12-lead ECG arrangement has the disadvantages that a large number of electrodes must be placed on the patient in positions which cover mainly the frontal parts of the myocardium. A large storage capacity is also required in order to record all the ECG signals from the electrodes. However, many doctors are familiar with the format of the 12-lead ECG.
Further, the normal procedure in the case of serious illness is to transport the patient to a hospital for diagnosis and treatment of the illness. However, it has proved to be advantageous to arrange for the nursing or ambulance staff to carry out the diagnosis and to start the treatment already at the place of patient pick-up. Such an arrangement likewise makes it possible to establish at an early stage whether a particular specialist competence and special equipment or the like are required, whereafter the patient may be transported straight to the place where such competence, equipment etcetera are available.
Such early diagnosis and treatment would be considerably facilitated, were the nursing staff given a possibility to carry with them a portable telemedicine device adapted to register signals from ECG and vector electrocardiogram (VCG) units and similar sensing equipment. A portable unit of this kind, which may be docked and thus be connected to a stationary communications network (LAN), which allows connection thereto of external measurement equipment, and which comprises a display device for visualization of the measurement results, is disclosed in U.S. Pat. No. 5,375,604.
However, this prior-art device is merely a passive unit and it is designed for reception and visualization only of signals from the measurement equipment. It cannot be used to establish active contact with and an exchange of information between the patient-attending staff and other individuals, a possibility which could be helpful in the diagnosis procedure as well as for the implementation of correct treatment measures. This is true particularly in the case of the above portable unit when used un-docked, in which case there is no communication with other equipment.
Furthermore, U.S. Pat. No. 5,441,047 describes a system according to which selected data on the patient is collected automatically, whereupon said data are forwarded via a stationary telecommunication network, such as a cable television network, to a centre where the diagnosis, monitoring or similar operations may be performed. The referred-to equipment is not, however, portable and in addition it comprises a plurality of independent components, and consequently this equipment is not adapted for ambulatory use and positioning onboard e.g. an ambulance. Nor is it adapted for active exchange of information between the nursing staff by the patient""s side and the personnel at the central unit.
In addition, there is a need for message exchanges between the nursing staff by the patient""s side and the personnel at the central unit as well as for possibilities of filling in certain types of pre-defined forms, such as patient case record files, already in the initial stage by the patient""s side. These needs are not met in the prior-art devices.
In addition, it would be desirable to enter data manually and preferably by one hand only, in a convenient, rapid and simple manner. It likewise would be desirable, to construct the entry means sufficiently small so as not to make the portable equipment unnecessarily bulky and unmanageable.
The present invention constitutes a substantial improvement in cardiac monitoring systems, and in particular, an improvement in cardiac monitoring systems providing an analysis and display of parameters relating to the condition of ischemic patients.
A myocardial analysis and monitoring method comprises steps of receiving a number of ECG signals relating to a heartbeat of at least one patient, converting the received number of ECG signals into three perpendicular ECG signals, determining an average heartbeat from the ECG signals, calculating a plurality of parameters related to a condition of each patient from the number of ECG signals, storing information representative of a value of the plurality of parameters related to the condition of each patient in storage, repeating the steps of determining the average heartbeat, calculating the plurality of parameters and storing said information for as long as ECG signals continue to be received or until the storage is full. At least a portion of the stored information is displayed as a graphical display, the graphical display representing a trend of at least one of the plurality of parameters. The displayed trend of the at least one of the plurality of parameters can be analyzed and at least one result of the analysis displayed.
The analyzing step may include detecting episodes, each episode comprising a predetermined number of trend values above a predetermined upper threshold level or below a predetermined lower threshold level occurring within a predetermined period of time of each other. The number of detected episodes can be displayed.
The analyzing step may include detecting an amount of time for a parameter to decline from a maximum value to a predefined value and displaying the detected amount of time. The detected amount of time may begin at a start of a patient therapy.
The analyzing step may include detecting an amount of recovery of a parameter at a predetermined time and displaying the detected amount of recovery.